(CBS NEWS)-- A gunman walked into Terminal 3 at Los Angeles International Airport Friday morning, pulled an assault rifle out of a bag and opened fire, killing a Transportation Security Administration officer at a security checkpoint and wounding three other TSA officers, authorities and law enforcement sources said.
Law enforcement sources tell CBS News the suspect was wounded in the incident but survived and is in custody. Preliminary information indicated that the suspect may have been an off-duty TSA employee, but a federal official told CBS News the suspect was not a current or former employee of the agency.
Interim Los Angeles Fire Chief Jim Featherstone told reporters during an afternoon news conference that first responders treated seven patients and transported six to area hospitals. Dr. Lynne McCullough of the Ronald Reagan UCLA Medical Center later said one male victim was in critical condition and two other male victims were in fair condition at the hospital.
Airport Police Chief Patrick Gannon said during the news conference that the gunman pulled an assault rifle out of a bag and began to open fire inside the terminal at 9:20 a.m.
"He proceeded up into the screening area, where TSA screeners are, and continued shooting," Gannon said.
The gunman went past the checkpoint into the secured area of the airport, Gannon said. Airport Police officers tracked the gunman inside the terminal and eventually engaged with him. He was successfully taken into custody after what Gannon described as an "officer-involved shooting."
"As you can imagine, a large amount of chaos took place during this entire incident," said Gannon. "We believe at this point that there was a lone shooter, that he acted, at least right now, was the only person that was armed in this incident."
Gannon said police completed a security sweep of the entire airport.
The suspect entered the terminal wearing military-like clothing when he opened fire, law enforcement sources told CBS News.
Passenger Robert Perez told CBS Los Angeles that TSA agents came through the terminal and yelled that a man had a gun.
"I heard popping and everybody dropped to the ground," Perez said.
Aerial video showed what appeared to be a TSA employee being wheeled away into an ambulance by police.
The airport announced on its Twitter feed that flight operations were temporarily held except for arriving flights.
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